This invention relates to a complex magnetic head and a method for manufacturing a magnetic head core of a complex magnetic head and, more particularly, to a complex magnetic head for use in a floppy disk drive (hereinafter referred to as FDD) in which a high recording density head core (hereinafter referred to as a first head core) and a low recording density head core (hereinafter referred to as a second head core) are combined in a unitary structure and a method for manufacturing a complex magnetic head core.
The magnetic head for use in an FDD includes a complex magnetic head in which two head cores of different recording densities are combined into a unitary structure. This is because there are two types of floppy disc (hereinafter referred to as FD) as a recording medium, i. e., a high density FDD of 120 Mbytes and a low density FDD of less than 2 Mbytes and different head cores are needed for writing and reading these two different types of FD with a common FDD unit.
FIG. 15 illustrates a complex magnetic head disclosed in Japanese Patent Laid-Open No. 63-103468, in which reference numeral 1 is a complex magnetic head, 2 is a first head core, 21 is a first R/W core, 22 is a first R/W gap, 23 is a first erase core and 24 is a first erase gap. Reference numeral 3 is a second head core, 31 is a second RAN core, 32 is a second R/W gap, 33 is a second erase core and 34 is a second erase gap. Reference numeral 4 is a slider.
In order to manufacture the complex magnetic head 1, the first head core 2 and the second head core 3 are separately prepared. Then, the first head core 2 and the second head core 3 are bonded together with the slider 4 interposed therebetween. At this time, the first head core 2, the second head core 3 and the slider 4 are bonded together with an appropriate positioning so that the first R/W gap 22, the first erase gap 24 and the like have appropriate gap depths (not shown).
One example of a method for preparing a head core will now be described. FIGS. 16a to 16e are views explaining the manufacturing method for the head core disclosed in Japanese Patent Laid-Open No. 3-263602. The head core manufactured by this method is different from the first head core 2 or the second head core 3 shown in FIG. 15 in terms of configuration but is substantially the same in terms of its function. In the figures, reference numeral 40 is a first core material, 41 is a first magnetic base plate provided with first gap grooves 41 a and 42 is a non-magnetic base plate. Also, reference numeral 43 is a second core material, 44 is a second magnetic base plate provided with second gap grooves 44a and coil grooves 44b. Reference numeral 45 is a chip-shaped head core prepared by this process.
First, the first core material 40 of FIG. 16a and the second core material 43 of FIG. 16b are joined with their first gap grooves 41 a and the second gap grooves 44a positioned in aligned opposition with each other so that a series of holes is formed between the first and second core materials 40 and 43 as shown in FIG. 16c. These holes defined by the first and the second gap grooves 41 a and 44a are then filled with a fused glass material (not shown). As illustrated in FIG. 16c, the assembly is cut along dot-and-dash lines into the configuration illustrated in FIG. 16d, which then is sliced along dot-and-dash lines shown in FIG. 16d to obtain a head core 45 shown in FIG. 16e.
When the head core is to be manufactured by the above-described conventional process shown in FIGS. 16a to 16e, a displacement can be easily generated between the first gap grooves 41 a and the second gap grooves 44a when the first core material 40 and the second core material 43 are bonded and the track surfaces of the head core manufactured are often out of alignment. This misalignment may not cause any problem for the second head core for the low density FDD which has a track width of 125 .mu.m, but can significantly affect the recording and reproducing operation of the high density FDD which has a track width of 8 .mu.m. That is, when the first head core 2 is manufactured by the conventional process illustrated in FIG. 16, many of head cores manufactured have the above-mentioned fatal track misalignment, resulting in a low yield.
Upon manufacturing the complex magnetic head 1 shown in FIG. 15, the first head core 2, the second head core 3 and the slider 4 are to be bonded to each other with an appropriate positioning so that the first RAN gap 22, the first erase gap 24 and the like have appropriate gap depths (not shown), so that the fine positional adjustments which are complicated and difficult must be achieved, lowering the productivity of the magnetic head.